Adhesive articles, such as bandages and tapes, are well known in the art and are commonly used as first aid wound dressings and other medical applications. Conventional adhesive bandages contain a central pad area (padstock) surrounded by adhesive areas. Particularly, adhesive bandages or tapes generally contain an elongated strip of cloth or plastic backing layer which has a pressure sensitive adhesive coated on one surface. A gauze or sponge pad is secured to the adhesive surface in a central location thereby serving as a wound covering material. The wound facing surface of the pad may be plastic coated or otherwise treated to prevent the padstock from adhering to the wound. Release strips are placed over the adhesive areas and typically the wound covering padstock and the entire assembly is enclosed in a sealed package and sterilized so as to be ready for use.
A disadvantage of adhesive articles in medical application is maceration. Normal human skin releases about 500 g/m2/24 hours of water in a resting state. When the water released by the skin is unable to evaporate then the skin becomes white in color and prune-like in appearance. After some time, the integrity of the skin could be weakened. Also the time for healing is the wound is often extended.
Rubber based pressure sensitive adhesives have the advantages of high adhesion and relatively low cost. The high adhesion is achieved without application of significant amounts of pressure. However, rubber based adhesives can be disadvantageous because they have inherently low breathability (i.e. low moisture vapor transmission rate (MVTR)). Therefore, such disadvantageous properties make rubber based adhesives generally unsuitable for skin contacting bandage applications.
U.S. Pat. No. 5,244,457 relates to a vented wound dressing made of a thin vapor-permeable sheet material having a pressure sensitive adhesive coating, the coating having repeating adhesive free areas. The adhesive covers at least 50% of the surface area of the thin vapor-permeable sheet material.
U.S. Pat. No. 5,641,506 relates to a medical patch material made of a support coated with a pressure sensitive hot melt adhesive coating using the gravure printing method. The medical patch material requires an adhesive-free area of at least 30% (between 30% and 60%), an adhesive coat weight between 30 and 160 g/m2, and a block copolymer adhesive having certain properties to achieve an MVTR of at least 2,000 g/m2/24 hours.
Canadian Patent 2,045,247 relates to a wound dressing made of a thin film carrying a discontinuous coating of a pressure sensitive adhesive, such as a rubber-based pressure sensitive adhesive, in such a manner so as to define adhesive-free areas. The film has an MVTR of at least 50 g/m2/24 hours, and preferably 500 g/m2/24 hours.